This invention relates generally to tools having moving parts which can be locked in a particular position for use with a pipe string disposed in a well and a method of using the same. More particularly, but not by way of limitation, this invention relates to a reciprocating ball valve tubing tester tool having a pressure responsive latching mechanism and a method of testing a pipe string with the same.
It is well known that there is the need for a tester valve tool used in a pipe string for controlling fluid flow by which the pipe string can be pressure tested to determine if there are any leaks in the pipe string. This is important so that any leaks can be detected relatively near the surface and fixed before higher pressure fluids are allowed to flow into or out of the pipe string. For example, such testing is needed prior to a squeeze-cementing or treating job. Because additional joints of pipe are added to the pipe string as the pipe string is lowered into the well, such testing often must be repeated so that the valve must be opened and closed several times before the ultimate work to be accomplished (e.g., the squeeze-cementing or treating job) is performed. After the testing is completed, however, the valve should be locked in a desired position, such as in an open position so that any subsequent, non-testing fluid flow is neither obstructed nor controlled by the tester valve. Therefore, there is the need for a tester valve with a locking or latching mechanism to lock the valve in such a desired position.
Tester valves of various types are well-known and types of valves which can be locked in an open or a closed position are also known; however, the locking or latching types of which I am aware are automatically operable in that locking or latching automatically occurs when the valve is moved to the position in which it is to be locked. That is, there is no additional controllable force required to be exerted on the latching device for it to operate once the valve is placed in the desired position. Thus, if such a valve is inadvertently moved to such locking position, it is automatically locked and cannot be unlocked until it is retrieved to the surface. Therefore, there is the need for a latching mechanism which must be positively acted upon or controlled other than by a passive biasing force which automatically operates as soon as the valve has moved to the locking position so that inadvertent (or even intentional) movement of the valve alone will not lock the valve. Such a positive acting force could be by an annular pressure applied under control from the surface, for example.
Such a novel valve should also be relatively simple to maintain, such as by constructing the latching mechanism so that it can be easily reset or released without disassembling the entire tool. By meeting the aforementioned needs, no J-slot need be used, thereby eliminating the maintenance problems associated with J-slots (e.g., lug wear).
Such a novel valve should also be constructed to enhance cost savings, such as by utilizing existing parts from other equipment and by compactly constructing the tool to reduce both material and machining costs.
Although the foregoing needs have been expressed with respect to a specific type of tool, namely a tester valve tool, such a latching mechanism should be constructed to have utility within other types of tools.